The long-term objectives of the research proposed are to determine the biological consequences of exposure to ultrasound on mammalian development. The studies proposed fall into two groups, the first being to evaluate the effects of ultrasound exposure of the ovary, by means of assessing preimplantation embryonic development in the mouse. Using this model, experiments have been designed to examine the effects of different levels of ultrasound on cell division, DNA synthesis, protein synthesis and the appearance of temporally-regulated cell surface molecules in the early embryo. The second group of experiments is concerned with the biological consequences to the post-implantation embryo following intrauterine exposure to ultrasound. They will test the hypothesis that ultrasound can cause irreversible damage to the developing central nervous system. Experiments have been designed to characterize CNS damage resulting from ultrasound exposure, to determine if damage is reversible, to demonstrate stage-related susceptibility to ultrasound and to determine whether effects are cumulative.